Mat S, 1885.] 



♦ KNOWLEDGE ♦ 



385 



It well exemplifies a peculiarity exhibited with more or 

 less distinctness in several species of this genus, viz., dis- 

 similarity in shape between the sexes ; the body of the 

 male is almost cylindrical, but that of the female inllated 

 or rounded at the sides, a feature which so alters her 

 appearance that a novice would be certain to divorce her 

 from her husband and consider her a distinct species. It 

 is a reddish brown, hard insect, with two narrow and 

 somewhat indistinct bands of whit© hairs on the elytra ; 

 the head is so much beut under the thorax that it cannot 

 be seen from above, so that the insect appears as though 

 it had been decapitated. The legs are long and straggling, 

 notwithstanding which the creature is slow and heavy in 

 its movements. The thorax is a good deal contracted 

 behind, appearing as though it had been tied round tight 

 while soft, and had hardened in that condition. By attending 

 to these few points of distinction, there can scarcely be 

 much difficulty in recognising a Plinus. 



This insect is a great foe to natural history collections; 

 whether of animils or plants ; and if by any chance it can 

 manage to effect a surreptitious entrance into such, it does 

 its best to execute the sentence " dust to dust " upon them. 

 But its tastes are varied, and range from such excellent 

 diet as the precious grain stored in granaries to the appa- 

 rently less attractive nutriment furnished by the threadbare 

 fabric of an old coat, the vegetable and the animal diet 

 seeming equally suited to its taste, though it was at one 

 time considered to be so largely an animal feeder as to 

 have been called by De Geer " vrillette carnassiire" the 

 carnivorous borer. 



Those who keep collections of foreign insects may some- 

 times have the privilege (?) of breeding (unintentionally) 

 exotic species of Ptlnus. Dried insects, when arriving 

 from abroad, sometimes contain in their carcases living 

 larvffi of PlinidfE, which fare sumptuously, though silently 

 and unobserved, upon the "dried meat" by which they 

 are surrounded — a veritable "life in death." I remember 

 on one occasion looking at a store box of exotic insects 

 that had not been opened for some time, and being 

 astonished at finding a colony of some dozen or so of a 

 beautiful bright red Ptimis, prettily ornamented with snow- 

 white spots, gaily disporting themselves amongst my stores, 

 quite regardless of such insecticides as were present. I 

 succeeded in tracing them to the huge carcase of a gigantic 

 beetle that I had unfortunately introduced into the society 

 without previously submitting to quarantine, and in whose 

 interior the larvae had evidently been holding carnival at 

 the time of his introduction. The Ptiyii turned out to be 

 a Polynesian specie?, which had thus completed their life 

 cycle many thousands of miles from their birth-place. On 

 their exclusion from their coleopterous host, they seemed 

 to have decided on a change of diet, and so had calmly 

 attacked the cork lining of the box, neatly excavating in 

 it a series of hollows, to the extreme detriment of its ap- 

 pearance, at least from my point of view. 



A most extraordinary trio of beetles now calls for notice. 

 They are closely allied to the genus Ptinus, and belong to 

 the same section of the family. They have very much the 

 appearance of spiders, for which, indeed, they are often 

 mistaken. The first is Xipiiis hololeucus (Fig. 2). It is a 

 small beetle, completely covered with a yellowish silky 

 down, and its resemblance to a spider is produced by three 

 peculiarities. A spider (which, be it remembered, is not 

 an insect at all, but a member of the class Arachnida) has 

 only two apparent divisions to its body, the hindermost of 

 which is usually highly convex and rounded at the sides, 

 and it has also eight legs. Now, though Xiplii.8 has dis- 

 tinctly the usual three divisions of an insect's body — 

 head, thorax, and abdomen — the first of these is so bent 



under the second that, as in Ptimts, it cannot be seen 

 from above ; and, in consr([uence, the body seems, like 

 that of a spider, to be composed of only two ])arts. The 

 elytra are vei-y convex above, and much inllated and rounded 

 at the side.s, and as the line of their junction is completely 

 obliterated, the abdomen acquires the globose and undivided 

 form of that of a s))ider. Again, the antenna-, which are 

 about equal in length to the legs, and, of course, on account 

 of the bending of the head, appear to come from underneath 

 as much as the legs themselves do, make up, with the usual 

 six legs, a number of appendages that may rcadUy be taken 

 for the eight legs of a spider. The imitation is so complete, 

 that, when only casually seen, the beetle might eavsily de- 

 ceive even those who are perfectly familiar with the differ- 

 ences between an insect and a spider. When once one 

 examines it closely, however, the apparent resemblances 

 vanish, and the creature is easily seen to be a true insect, 

 and is moreover found to be as hard bodied as a Ptinus, in- 

 stead of exhibiting the soft and yielding integument of a 

 spider. 



Fig. 2.— Niptus hololeucus. Fig. 3. — Scales of Niptns. 



It occurs commonly in houses, often in considerable 

 numbers. It is not a wood-borer, but feeds on anything it 

 can come across that is at all edible, and, in consequence, 

 mo.st frequents cupboards where stores of provisions are 

 kept. It was once found in great numbers in a plate cup- 

 board, where it was saicf, though with what degree of 

 justice it is very difficult to understand, to have done con- 

 siderable damage to the silver .stored there. It has no 

 wings, and is therefore not much of a wanderer, £0 that 

 when a colony has once established itself in any part of a 

 house, the successive generations are likely to remain in 

 those quarters as long as provisions last, unless forcibly 

 ejected. It is probably not a truly indigenous insect, but, 

 like many others, has been inqiorted from abroad, so that 

 although not blessed with great powers of locomotion, it 

 has yet been a considerable traveller. 



Under the microscope the yellow clothing of Xiptus is 

 seen to be composed of two totally distinct elements. 

 There are a number of longitudinal row.s of long hairs or 

 bristles, projecting considerably above the general surface 

 and pointing backwards ; and beneath these, closely cover- 

 ing the body, a quantity of tiny yellow scales overlapping 

 one another. Each scale (Fig. 3) is Wimtly pointed at the 

 place of its attachment to the body, and at the outer 

 extremity is usually produced into two long pointed pro- 

 jections at the sides with a shorter one between them. 

 Not unfrequently the central process is also clefc. When 

 the scales are removed the body beneath is seen to be highly 

 polished and of a deep chestnut colour. 



{To he continued) . ■■ '■ 



Messes. C. Isler & Co., of Sonthwark-street, have secnred the 

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